Print component with memory circuit

ABSTRACT

A memory circuit for a print component including a plurality of I/O pads, including an analog pad, to connect to a plurality of signal paths which communicate operating signals to the print component. A memory component stores memory values associated with the print component, and a control circuit, in response to a sequence of operating signals on the I/O pads representing a memory read, provides an analog signal to the analog pad to provide an analog electrical value at the analog pad representing stored memory values selected by the memory read.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Stage Application of PCT ApplicationNo. PCT/US2019/044446, filed Jul. 31, 2019, entitled “PRINT COMPONENTWITH MEMORY CIRCUIT,” which claims priority to PCT Application No.PCT/US2019/016725, filed Feb. 6, 2019, entitled “MULTIPLE CIRCUITSCOUPLED TO AN INTERFACE” and PCT Application No. PCT/US2019/016817,filed Feb. 6, 2019, entitled “COMMUNICATING PRINT COMPONENT”.

BACKGROUND

Some print components may include an array of nozzles and/or pumps eachincluding a fluid chamber and a fluid actuator, where the fluid actuatormay be actuated to cause displacement of fluid within the chamber. Someexample fluidic dies may be printheads, where the fluid may correspondto ink or print agents. Print components include printheads for 2D and3D printing systems and/or other high precision fluid dispense systems.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block and schematic diagram illustrating a memory circuitfor a print component, according to one example.

FIG. 2 is a block and schematic diagram illustrating a memory circuitfor a print component, according to one example.

FIG. 3 is a block and schematic diagram illustrating a memory circuitfor a print component, according to one example.

FIG. 4 is a block and schematic diagram illustrating a memory circuitfor a print component, according to one example.

FIG. 5 is a block and schematic diagram illustrating a memory circuitfor a print component, according to one example.

FIGS. 6A and 6B are block and schematic diagrams illustrating flexiblewiring substrate for connecting a memory circuit to a print component,according to one examples.

FIG. 7 is a block and schematic diagram illustrating a memory circuitfor a print component, according to one example.

FIG. 8 is a block and schematic diagram illustrating a memory circuitfor a print component, according to one example.

FIG. 9 is a block and schematic diagram illustrating a memory circuitfor a print component, according to one example.

FIG. 10 is a block and schematic diagram illustrating a memory circuitfor a print component, according to one example.

FIG. 11 is a block and schematic diagram illustrating flexible wiringsubstrate for connecting a memory circuit to a print component,according to one example.

FIG. 12 is a block and schematic diagram illustrating a memory circuitfor a print component, according to one example.

FIG. 13 is a block and schematic diagram illustrating a memory circuitfor a print component, according to one example.

FIG. 14 is a block and schematic diagram illustrating flexible wiringsubstrate for connecting a memory circuit to a print component,according to one example.

FIG. 15 is a block and schematic diagram illustrating a fluid ejectionsystem, according to one example.

Throughout the drawings, identical reference numbers designate similar,but not necessarily identical, elements. The figures are not necessarilyto scale, and the size of some parts may be exaggerated to more clearlyillustrate the example shown. Moreover the drawings provide examplesand/or implementations consistent with the description; however, thedescription is not limited to the examples and/or implementationsprovided in the drawings.

DETAILED DESCRIPTION

In the following detailed description, reference is made to theaccompanying drawings which form a part hereof, and in which is shown byway of illustration specific examples in which the disclosure may bepracticed. It is to be understood that other examples may be utilizedand structural or logical changes may be made without departing from thescope of the present disclosure. The following detailed description,therefore, is not to be taken in a limiting sense, and the scope of thepresent disclosure is defined by the appended claims. It is to beunderstood that features of the various examples described herein may becombined, in part or whole, with each other, unless specifically notedotherwise.

Example fluidic dies may include fluid actuators (e.g., for ejecting andrecirculating fluid), where the fluid actuators may include thermalresistor based actuators, piezoelectric membrane based actuators,electrostatic membrane actuators, mechanical/impact driven membraneactuators, magneto-strictive drive actuators, or other suitable devicesthat may cause displacement of fluid in response to electricalactuation. Fluidic dies described herein may include a plurality offluid actuators, which may be referred to as an array of fluidactuators. An actuation event may refer to singular or concurrentactuation of fluid actuators of the fluidic die to cause fluiddisplacement. An example of an actuation event is a fluid firing eventwhereby fluid is jetted through a nozzle.

In example fluidic dies, the array of fluid actuators may be arranged insets of fluid actuators, where each such set of fluid actuators may bereferred to as a “primitive” or a “firing primitive.” The number offluid actuators in a primitive may be referred to as a size of theprimitive. In some examples, the set of fluid actuators of eachprimitive are addressable using a same set of actuation addresses, witheach fluid actuator of a primitive corresponding to a differentactuation address of the set of actuation addresses, with the addressesbeing communicated via an address bus. In some examples, during anactuation event, in each primitive, the fluid actuator corresponding tothe address on the address bus will actuate (e.g., fire) in response toa fire signal (also referred to as a fire pulse) based on a state of theselect data (e.g., a select bit state) corresponding to the primitive(sometimes also referred to as nozzle data or primitive data).

In some cases, electrical and fluidic operating constraints of a fluidicdie may limit the number of fluid actuators of which can be actuatedconcurrently during an actuation event. Primitives facilitate selectingsubsets of fluid actuators that may be concurrently actuated for a givenactuation event to conform to such operating constraints.

By way of example, if a fluidic die includes four primitives, with eachprimitive having eight fluid actuators (with each fluid actuatorcorresponding to a different address of a set of addresses 0 to 7, forexample), and where electrical and fluidic constraints limit actuationto one fluid actuator per primitive, a total of four fluid actuators(one from each primitive) may be concurrently actuated for a givenactuation event. For example, for a first actuation event, therespective fluid actuator of each primitive corresponding to address “0”may be actuated. For a second actuation event, the respective fluidactuator of each primitive corresponding to address “5” may be actuated.As will be appreciated, such example is provided merely for illustrationpurposes, where fluidic dies contemplated herein may comprise more orfewer fluid actuators per primitive and more or fewer primitives perdie.

Example fluidic dies may include fluid chambers, orifices, and/or otherfeatures which may be defined by surfaces fabricated in a substrate ofthe fluidic die by etching, microfabrication (e.g., photolithography),micromachining processes, or other suitable processes or combinationsthereof. Some example substrates may include silicon based substrates,glass based substrates, gallium arsenide based substrates, and/or othersuch suitable types of substrates for microfabricated devices andstructures. As used herein, fluid chambers may include ejection chambersin fluidic communication with nozzle orifices from which fluid may beejected, and fluidic channels through which fluid may be conveyed. Insome examples, fluidic channels may be microfluidic channels where, asused herein, a microfluidic channel may correspond to a channel ofsufficiently small size (e.g., of nanometer sized scale, micrometersized scale, millimeter sized scale, etc.) to facilitate conveyance ofsmall volumes of fluid (e.g., picoliter scale, nanoliter scale,microliter scale, milliliter scale, etc.).

In some examples, a fluid actuator may be arranged as part of a nozzlewhere, in addition to the fluid actuator, the nozzle includes anejection chamber in fluidic communication with a nozzle orifice. Thefluid actuator is positioned relative to the fluid chamber such thatactuation of the fluid actuator causes displacement of fluid within thefluid chamber that may cause ejection of a fluid drop from the fluidchamber via the nozzle orifice. Accordingly, a fluid actuator arrangedas part of a nozzle may sometimes be referred to as a fluid ejector oran ejecting actuator.

In some examples, a fluid actuator may be arranged as part of a pumpwhere, in addition to the fluidic actuator, the pump includes a fluidicchannel. The fluidic actuator is positioned relative to a fluidicchannel such that actuation of the fluid actuator generates fluiddisplacement in the fluid channel (e.g., a microfluidic channel) toconvey fluid within the fluidic die, such as between a fluid supply anda nozzle, for instance. An example of fluid displacement/pumping withina die may sometimes be referred to as micro-recirculation. A fluidactuator arranged to convey fluid within a fluidic channel may sometimesbe referred to as a non-ejecting or microrecirculation actuator.

In one example nozzle, the fluid actuator may comprise a thermalactuator, where actuation of the fluid actuator (sometimes referred toas “firing”) heats the fluid to form a gaseous drive bubble within thefluid chamber that may cause a fluid drop to be ejected from the nozzleorifice. As described above, fluid actuators may be arranged in arrays(such as columns), where the actuators may be implemented as fluidejectors and/or pumps, with selective operation of fluid ejectorscausing fluid drop ejection and selective operation of pumps causingfluid displacement within the fluidic die. In some examples, the arrayof fluid actuators may be arranged into primitives.

Some fluidic dies receive data in the form of data packets, sometimesreferred to as fire pulse groups or as fire pulse group data packets. Insome examples, such data packets may include configuration data andselect data. In some examples, configuration data includes data forconfiguring on-die functions, such as address bits representing anaddress of fluid actuators to be actuated as part of a firing operation,fire pulse data for configuring fire pulse characteristics, and thermaldata for configuring thermal operations such as heating and sensing. Insome examples, the data packets are configured with head and tailportions including the configuration data, and a body portion includingthe select (primitive) data. In example fluidic dies, in response toreceiving a data packet, on-die control circuitry employs addressdecoders/drivers to provide the address on an address line, activationlogic to activate selected fluid actuators (e.g., based on the address,select data, and a fire pulse), and configuration logic to configureoperations of on-die functions, such as fire pulse configuration, cracksensing and thermal operations based on configuration data and a modesignal, for instance.

In addition to fluid actuators, some example fluidic dies include on-diememory (e.g., non-volatile memory (NVM)) to communicate information(e.g., memory bits) with external devices, such as a printer, to assistin controlling operation of the fluidic, including operation of fluidactuators and other devices (e.g., heaters, crack sensors) forregulating fluid ejection. In examples, such information may includethermal behavior, offsets, region information, a color map, fluidlevels, and a number of nozzles, for example.

Memories typically include overhead circuitry (e.g., address, decode,read, and write modes, etc.) which are costly to implement and consumerelatively large amounts of silicon area on a die. However, sincesimilar circuitry is employed in selecting, actuating, and transferringdata to an array of fluid actuators, some example fluidic diesmultipurpose portions of the control circuitry for selecting andtransferring data to fluid actuators (including portions of a high speeddata path, for example) to also select memory elements of a memoryarray.

To further save space and reduce complexity associated with multi-busarchitectures, some example fluidic dies employ a single lane analog buswhich is communicatively connected in parallel with the memory elementsto read and write information to/from the memory elements over theshared single lane analog bus (which is also sometimes referred to as asense bus). In some examples, the single-lane bus is able to read/writeto memory elements individually or to different combinations of memoryelements in parallel. Additionally, some example fluidic dies includedevices such as crack sensors, temperature sensors, and heating elementsthat may also be connected to the signal-lane analog bus for sensing andcontrol.

In example fluidic dies having on-die memories, in addition tocommunicating select data to select fluid actuators for actuation aspart of a fluid actuation operation, data packets may communicate selectdata to select memory elements which are to be accessed as part of amemory access operation (e.g., read/write operations). To differentiatebetween different operating modes, such as between a fluid actuationmode and a memory access mode, example fluidic dies may employ differentoperating protocols for different modes of operation. For example, afluid die may employ one protocol sequence of operating signals, such asdata (e.g., data packets) received via data pads (DATA), a clock signalreceived which clock pad (CLK), a mode signal received via a mode pad(MODE), and a fire signal received a fire pad (FIRE), to identify fluidactuator operation, and another sequence of such signals to identifymemory access operations (e.g., read and write).

In example fluidic dies, on-die memory elements may beone-time-programmable (OTP) elements. During manufacture, informationmay be written to the memory elements late in the manufacturing process,including after a fluidic die may have been arranged as a part of aprinthead or pen. If the memory is found to be defective (e.g., to haveone or more failed bits that will not program properly), the fluidic diemay not function properly, such that the fluidic die, printhead, and penare also defective. Additionally, even though the overhead circuitry ofthe memory may be shared with fluid actuator selection and activationcircuitry, the inclusion of on-die memory elements consumes siliconearea and increases dimensions of the fluidic die.

The present disclosure, as will be described in greater detail herein,provides a print component, such as a printhead or a print pen, forexample, including a fluidic die having an array of fluid actuators. Thefluidic die is coupled to a number of input/output (I/O) terminalscommunicating operating signals for controlling the operation of thefluidic die, including ejection operations of the fluidic actuators, theI/O terminals including an analog sense terminal. The print componentincludes a memory die, separate from the fluidic die, coupled to the I/Oterminals, the memory die to store memory values associated with theprint component, such as manufacturing data, thermal behavior, offsets,region information, a color map, a number of nozzles, and fluid type,for example. According to one example, in response to observingoperating signals on I/O terminals representing a memory access sequenceof the stored memory values, the memory die provides an analog signal onthe sense terminal based on the stored memory values corresponding tothe memory access sequence.

As will be described in greater detail herein, in one example, thememory die replaces or substitutes for a defective memory array on thefluidic die, thereby enabling the fluidic die, and a print componentemploying the fluidic die, such as a print pen, for example, to remainoperational. In another example, the memory die can be employed insteadof a memory array on the fluidic die, thereby enabling the fluidic dieand a printhead employing the fluidic die to be made smaller. In anotherexample, the fluidic die can be employed to supplement a memory array onthe fluidic die (e.g., to expand the memory capacity).

FIG. 1 is a block and schematic diagram generally illustrating a memorycircuit 30, according to one example of the present disclosure, for aprint component, such as a print component 10. Memory circuit 30includes a control circuit 32, and a memory component 34 storing anumber of memory values 36 associated with operation of print component10. Memory component 34 may comprise any suitable storage element,including any number of non-volatile memories (NVM), such as EPROM,EEPROM, flash, NV RAM, fuse, for example. In one example, memory values36 may be values stored as a lookup table, where such lookup table maybe an array of indexing data, with each memory value having acorresponding address or index. In examples, each memory value 36represents a data bit having a bit state of “0” or “1”, or an analogvalue (e.g., a voltage or a current) corresponding to a “0” and “1”. Inexamples, memory circuit 30 is a die.

Memory circuit 30 includes a number of input/output (I/O) pads 40 toconnect to a plurality of signal paths 41 which communicate operatingsignals to print component 10. In one example, the plurality of I/O pads40 includes a CLK Pad 42, a DATA Pad 44, a FIRE Pad 46, a MODE Pad 48,and an Analog Pad 50, which will be described in greater detail below.In examples, control circuit 32 monitors the operating signals conveyedto print component 10 via I/O pads 40. In one example, upon observing asequence of operating signals representing a memory read (e.g., a “read”protocol), control circuit 32 provides an analog electrical signal toAnalog Pad 50 to provide an analog electrical value at Analog Pad 50representing the stored memory values 36 selected by the memory read. Inexamples, the analog electrical signal provided to Analog Pad 50 may beone of an analog voltage signal and an analog current signal, and theanalog electrical signal may be one of a voltage level and a currentlevel. In examples, Analog Pad 50 may be an analog sense pad connectedto an analog sense circuit, and is sometimes referred to herein as SENSEpad 50.

In one example, upon observing a sequence of operating signalsrepresenting a memory write (a “write” protocol), control circuit 32adjusts the values of the stored memory values.

FIG. 2 is a block and schematic diagram generally illustrating memorydie 30, according to one example, for a print component 10, where printcomponent 10 can be a print pen, a print cartridge, a print head, or mayinclude a number of printheads. In examples, the print component 10 maybe removable and replaceable in a printing system. The print componentmay be a refillable device, and may include a tank, chamber, orcontainer for fluid, such as ink. The print component may include areplaceable container for fluid.

In one example, print component 10 includes a fluid ejection circuit 20,a memory circuit 30, and a number of input/output (I/O) pads 40. Fluidejection circuit ejection circuit 20 includes an array 24 of fluidactuators 26. In examples, fluid actuators 26 may be arranged to form anumber of primitives, with each primitive having a number of fluidactuators 26. A portion of fluid actuators 26 may be arranged as part ofa nozzle for fluid ejection, and another portion arranged as part of apump for fluid circulation. In one example, fluidic ejection circuit 20comprises a die.

In one example, I/O pads 40 of memory circuit 30 include CLK Pad 42,DATA Pad 44, FIRE Pad 46, MODE Pad 48, and Analog Pad 50 which connectto a plurality of signal paths which convey a number of digital andanalog operating signals for operating fluidic ejection circuit 20between print component 10 and a separate device, such as a printer 60.CLK pad 42 may convey a clock signal, DATA pad 44 may convey dataincluding configuration data and selection data, including in the formof fire pulse group (FPG) data packets, FIRE pad may communicate a firesignal, such as a fire pulse, to initiate an operation of fluidicejection circuit 20 (such as, for example, operation of selected fluidactuators 24), MODE pad 48 may indicate different modes of operation offluidic ejection circuit 20, and SENSE pad 50 may convey analogelectrical signals for sensing and operation of sensing elements fluidicejection circuit 20 (such as, for example, crack sensors, thermalsensors, heaters) and memory elements of fluidic ejection circuit 20,such as will be described in greater detail below.

In one example, memory values 36 of memory component 34 of memorycircuit 30 are memory values associated with print component 10,including memory values associated with the operation of fluid ejectioncircuit 20, such as a number of a nozzles, ink levels, operatingtemperatures, manufacturing information, for example. In examples,similar to that described above, upon observing a sequence of operatingsignals representing a memory read (e.g., a “read” protocol), controlcircuit 32 provides an analog electrical signal to Analog Pad 50 toprovide an analog electrical value at Analog Pad 50 representing thestored memory values 36 selected by the memory read.

In an example where fluid ejection circuit 20 is implemented as afluidic die, by disposing memory circuit 30 separately from fluidicejection circuit 20, such fluidic die can be made with smallerdimensions, such that a printhead including a fluidic die 20 may havesmaller dimensions.

In one example, fluidic ejection circuit 20 may include a memory array28 including a number of memory elements 29 storing memory valuesassociated with the operation of print component 10 and fluidic ejectioncircuit 20. In one case, where memory array 28 includes defective memoryelements 29, memory circuit 30 may serve as a substitute memory (areplacement memory) for memory array 28, with stored memory values 36replacing values stored by memory elements 29. In another case, memorycircuit 30 may supplement memory array 28 (increase the storage capacityassociated with fluidic ejection circuitry 20). In one example, as willbe described in greater detail below, such as when being employed toreplace or substitute for a defective on-die memory array 28, memorycircuit 30 may be connected to print component 10 via an overlay wiringsubstrate (e.g., a flexible overlay) which includes pads that overlayand contact the number of I/O pads 40.

FIG. 3 is a block and schematic diagram generally illustrating memorycircuit 30 connected to a print component 10 including fluid ejectioncircuit 20 having a memory array 28, and a memory circuit 30 (e.g., amemory die), according to one example of the present disclosure. In onecase, as will be described in greater detail below, memory circuit 30replaces memory array 28 of fluidic ejection circuit 20, such as whenmemory array 28 is defective, for example.

Fluidic ejection circuit 20 includes array 24 of fluidic actuators 26,and an array 28 of memory elements 29. In one example, the array 24 offluid actuators 26 and the array 28 of memory elements 29 are eacharrayed to form a column, with each column arranged into groups referredto as primitives, with each primitive P₀ to P_(M) including a number offluid actuators, indicated as fluid actuators F₀ to F_(N), and a numberof memory elements, indicated as memory elements M₀ to M_(N). Eachprimitive P0 to PM employs a same set of addresses, illustrated asaddresses A0 to AN. In one example, each fluid actuator 26 has acorresponding memory element 29 addressable by the same address, such asfluid actuator F₀ and memory element M₀ of primitive P₀ eachcorresponding to address A₀.

In one example, each fluid actuator 26 may have more than onecorresponding memory element 29, such as two corresponding memoryelements 29, as indicated by the dashed memory elements 29, where thearray 28 of memory elements is arranged to form two columns of memoryelements 29, such as columns 28 ₁ and 28 ₂, with each additional memoryelement sharing the corresponding address. In other examples, each fluidactuator 26 may have more than two corresponding memory elements 29,where each additional memory element 29 is arranged as part of anadditional column of memory elements 29 of memory array 28. According toone example, as will be described in greater detail below, where morethan one column of memory elements 29 are employed such that more thanone memory element 29 shares a same address, each column of memoryelements 29 may be separately addressed (or accessed) using column bitsin a fire pulse group data packet to identify a column to be accessed.

In one example, fluidic ejection circuit 20 may include a number ofsensors 70, illustrated as sensors S₀ to S_(X), to sense a state offluidic ejection circuit 30, such as temperature sensors and cracksensors, for example. In one example, as will be described in greaterdetail below, memory elements 29 and sensors 70 may be selectivelycoupled to sense pad 50, such as via a sense line 52, for access, suchas by printer 60. In one example, communication of information toprinter 60, such as measurements of cracks and temperatures in regionsof fluidic ejection circuit 20, and information stored by memoryelements 29 (e.g., thermal behavior, offsets, color mapping, number ofnozzles, etc.), enables computation and adjustment of instructions foroperation of fluidic ejection circuit 20 (including fluid ejection)according to detected conditions.

In one example, fluidic ejection circuit 20 includes control circuit 80to control the operation of the array 24 of fluid actuators 26, thearray 28 of memory elements 29, and sensors 70. In one example, controlcircuit 80 includes an address decoder/driver 82, activation/selectionlogic 84, a configuration register 86, a memory configuration register88, and write circuitry 89, with address decoder/driver 82 andactivation/selection logic 84 being shared to control access to thearray 24 of fluid actuators 26 and the array 28 of memory elements 29.

In one example, during a fluid actuation event, control logic 80receives a fire pulse group (FPG) data packet via data pad 44, such asfrom printer 60. In one case, the FPG data packet has a head portionincluding configuration data, such as address data, and a body portionincluding actuator select data, each select data bit having a selectstate (e.g., a “1” or a “0”) and each select data bit corresponding to adifferent one of the primitives P₀ to P_(M). Address decoder/driver 82decodes and provides the address corresponding data packet address data,such as on an address bus, for example. In one example, in response toreceiving a fire pulse via fire pad 46 (such as from printer 60), ineach primitive P0 to PM, activation logic 84 fires (actuates) the fluidactuator corresponding to the address provided by address decoder/driver82 when the corresponding select bit is set (e.g., has state of “1”).

Similarly, according to examples, during a memory access operation,control logic 80 receives a fire pulse group (FPG) data packet via datapad 44, such as from printer 60. However, rather than including actuatorselect data, during a memory access operation, the body portion of theFPG data packet includes memory select data, with each select data bithaving a select state (e.g., “0” or “1”) and corresponding andcorresponding to a different one of the primitives P0 to PM. In oneexample, in response to receiving a fire pulse via fire pad 46, in eachprimitive P0 to PM, activation logic 84 fires connects the memoryelement 29 corresponding to the address provided by addressdecoder/driver 82 to sense line 52 when the corresponding select bit isset (e.g., has state of “1”).

In a case where the memory access operation is a “read” operation, ananalog response of the memory element 29 (or elements 29) connected tosense line 52 to an analog sense signal (e.g., a sense current signal ora sense voltage signal) provided on sense line 52, such as by printer 60via sense pad 50, is indicative of a state of the memory element 29 (orelements). In a case where the memory access operation is a “write”operation, memory elements 29 connected to sense line 52 may beprogrammed to a set state (e.g., to a “1” from a “0”) by an analogprogram signal provided on sense line 52, such as by printer 60 viasense pad 50, or by a write circuit 89 integral with fluidic ejectioncircuit 20.

During a read operation, a single memory element 29 may be connected tosense line 52 and be read, or a combination (or subset) of memoryelements 29 may be connected in parallel to sense line 52 and be readsimultaneously based on an expected analog response to an analog sensesignal. In examples, each memory element 29 may have known electricalcharacteristics when in a programmed state (e.g., set to a value of “1”)and an unprogrammed state (e.g., having a value of “0”). For example, inone case, memory elements 29 may be floating gate metal-oxidesemiconductor field-effect transistors (MOSTFETs) having a relativelyhigh resistance when unprogrammed, and a relatively lower resistancewhen programmed. Such electrical properties enable known responses toknown sense signals to be indicative of a memory state of the memoryelement 29 (or elements), during a read operation.

For example, if a fixed sense current is applied to sense line 52, avoltage response may be measured that is indicative of a memory state ofa selected memory element 29, or memory elements 29. When more than onememory element 29 is connected in parallel to sense line 52, eachadditional memory element reduces the resistance, which reduces a sensevoltage response at sense pad 50 by a predictable amount. As such,information (e.g., program state) may be determined about thecombination of selected memory elements 29 based on the measured sensevoltage. In examples, a current source internal to fluidic ejectioncircuit 20 may be used to apply the sense current. In other examples, acurrent source external to fluidic ejection circuit 20 (e.g., printer 60via sense pad 50) may be used.

In a corresponding way, if a fixed sense voltage is applied a currentresponse may be measured that is indicative of a memory state of aselected memory element 29 (or memory elements 29). When more than onememory element 29 is connected in parallel to sense line 52, eachadditional memory element 29 reduces the resistance, which increases asense current at sense pad 50 by a predictable amount. As such,information (e.g., program state) may be determined about thecombination of selected memory elements 29 based on the measured sensecurrent. In examples, a voltage source internal to fluidic ejectioncircuit 20 may be used to apply the sense voltage. In other examples, avoltage source external to fluidic ejection circuit 20 (e.g., printer 60via sense pad 50) may be used.

In one case, to enable fluidic ejection circuit 20 to identify a memoryaccess operation so that information is not inadvertently written tomemory array 29 during other operations, such as a fluid actuationoperation, a unique memory access protocol is used which includes aspecific sequence of operating signals received via I/O pads 40. In oneexample, the memory access protocol begins with DATA pad 44 being raised(e.g., raised to a relatively higher voltage). With DATA pad 44 stillbeing raised, MODE pad 48 is raised (e.g., a mode signal on MODE pad 48is raised). With the DATA pad 44 and Mode pad 48 raised, control logic80 recognizes that an access of configuration register 86 is to occur. Anumber of data bits are then shifted into configuration register 86 fromDATA pad 44 with a clock signal on CLK pad 42. In one example,configuration register 86 holds a number of bits, such as 11 bits, forexample. In other examples, configuration register 86 may include morethan or few than 11 bits. In one example, one of the bits in controlregister 86 is a memory access bit.

A FPG data packet is then received via DATA pad 44, with the select bitsin the body portion of the data packs representing memory element 29select bits. In one example, the FPG data packet further includes aconfiguration bit (e.g., in a head or tail portion of the data packet)that, when set, indicates that the FPG is a memory access FPG. Whencontrol logic 80 recognizes that both the memory enable bit inconfiguration register 86 and the memory access configuration data bitin the received FPG packet are “set”, control logic 80 enables memoryconfiguration registration (MCR) 88 to receive data via Data pad 44 in afashion similar to which configuration register 86 received data bits(as described above). According to one example, upon recognizing thatboth the memory enable bit in configuration register 86 and the memoryaccess configuration data bit in the received FPG packet are “set”, anumber of data bits are shifted into memory configuration register 88from DATA pad 44, including a column enable bit to enable a column 28 ofmemory bits to be accessed, and a read/write enable bit indicatingwhether the memory access is a read or a write access (e.g., a “0”indicating a memory read and a “1” indicating a memory write). In oneexample, where fluidic ejection circuit 20 has a memory array 28 havingmore than one column of memory elements 29, such as columns 28 ₁ and 28₂, configuration data of the FPG data packet communicating the memoryselect data includes column selection bits to identify which column 28of data elements is being accessed. The column enable bit of memoryconfiguration register 88 and the column selection bit of the FPG datapacket together enable the selected column 28 to be accessed for amemory operation.

After loading data into memory configuration register 88, the fire pulseon FIRE pad 44 is raised, and each memory element 29 corresponding tothe address represented in the header of the FPG and having acorresponding memory select bit in the body portion of the FPG which isset (e.g., having a value of “1”) is connected to sense bus 52 for aread or a write access, as indicated by the state of the read/write bitof the memory configuration register.

In one example, a read operation of a crack sensor 70 of fluid ejectioncircuit 30 has a protocol similar to that of a read operation of memoryelements 29. Data pad 44 is raised, followed by the mode signal on MODEpad 48 being raised. A number of data bits are then shifted intoconfiguration registration 86. However, in lieu of a configuration databit corresponding to a read operation of a memory element 29 being setin configuration register 86, a configuration data bit corresponding toa read operation of a crack sensor 70 is set. After data has beenshifted into configuration register 86, a FPG is received by controllogic 80, where all data bits of the body portion of the FPG have anon-select value (e.g. a value of “0”). The fire pulse signal on FIREpad 46 is then raised, and the crack sensor 70 is connected to senseline 52. An analog response of crack sensor 70 to an analog sense signalon sense line 52 is indicative of whether crack sensor 70 is detecting acrack (e.g., an analog voltage sense signal produces an analog responsecurrent signal, and an analog current sense signal produces an analogresponse voltage signal).

In one example, a read operation of a thermal sensor 70 is carried outduring a fluid ejection operation. In one case, a configuration data bitcorresponding to a particular thermal sensor is set in a head or tailportion of the FPG data packet, while the body portion of the FPGincludes actuator select data bits, one for each primitive P₀ to P_(M),and having a state indicative of which fluid actuators 26 are to beactuated. When the fire pulse signal on FIRE pad 46 is raised, theselected fluid actuators 26 are fired, and the selected thermal sensor(e.g., a thermal diode) is connected to sense line 52. An analog sensesignal applied to the selected thermal sensor via sense line 52 resultsin an analog response signal on sense line 52 indicative of thetemperature of the thermal sensor.

In one example, where memory array 28 of fluidic ejection circuit 20 mayinclude defective memory elements 29 storing incorrect memory values,memory circuit 30 may be connected in parallel with fluidic ejectioncircuitry 20 to I/O terminals 40 with the memory values 36 of memorycomponent 34 to serve as a replacement memory for memory array 28 and tostore correct memory values. In one example, control circuit 32 monitorsthe operating signals received via I/O pads 42. In one case, uponrecognizing a memory access sequence, such as described above, controlcircuit 32 checks the status of the read/write bit provided to memoryconfiguration register 88 via DATA pad 44.

In one example, where the memory access is a “write” operation, controlcircuit 32 checks the state of the memory select bits in the bodyportion of the FPG received via DATA pad 44 to determine which memoryelements 29 are indicated as being programmed (e.g., have correspondingselect bit which is set (e.g., has a value of “1”). Control circuit 32then updates the corresponding memory values 36 of memory component 34to reflect any changes in memory values 36 due to the write operation.

In one example, where the memory access is a “read” operation, controlcircuit 32 checks the state of the memory select bits in the bodyportion of the FPG received via DATA pad 44 to determine which memoryelements 29 are indicated as being programmed. Control circuit 32 thenchecks the corresponding memory values 36 in memory component 34 anddetermines the type of analog sense signal present SENSE pad 50. In oneexample, in response to the detected analog sense signal, and based onthe memory values to be read, control circuit 32 drives an analogresponse signal on sense line 52 and SENSE pad 50 indicative of thevalues of memory values 36.

For example, in a case where an analog sense current is provided onsense line 52 via SENSE pad 50, such as by printer 60, and a singlememory value is being read, control circuit provides an analog voltageresponse on sense line 52 which is indicative of the value of the signalmemory value being read. For example, if a single memory value is beingread, the analog voltage response provided on sense line 52 by controlcircuit 32 may be a relatively high voltage for an unprogrammed memoryvalue, and may be a relatively lower voltage for a programed memoryvalue. In one example, control circuit 32 provides the analog voltageresponse on sense line 52 having a value equal to an expected responsein view of the known characteristics of memory elements 29, the numberof memory elements 29 being read in parallel, and the analog sensesignal.

By monitoring operating signals on I/O pads 40 to identify memory accessoperation (e.g., read/write operations) in order to maintain and updatememory values 36, and to provide expected analog response signals onsense line 52 in response to memory read operations, memory circuit 30is indistinguishable from memory array 28 of fluidic ejection circuit 20to a device accessing print component 10, such as printer 60.

FIG. 4 is a block and schematic diagram illustrating memory circuit 30connected to print component 10, according to one example. In theexample of FIG. 4, print component 10 includes a number of fluidejection circuits 20, illustrated as fluidic ejection circuits 20 ₀, 20₁, 20 ₂ and 20 ₃, each including an array of fluid actuators 24,illustrated as actuator arrays 24 ₀, 24 ₁, 24 ₂, and 24 ₃, and eachincluding a memory array 28, illustrated as memory arrays 28 ₀, 28 ₁, 28₂ and 28 ₃. In one example, each fluidic ejection circuit 20 comprises aseparate fluidic ejection die, with each die providing a different colorink. For example, fluidic ejection die 20 ₀ may be a cyan die, fluidicejection die 20 ₁ may be a magenta die, fluidic ejection die 20 ₂ may bea yellow die, and fluidic ejection die 20 ₃ may be a black die. Inexample, fluidic ejection dies 20 ₀, 20 ₁ and 20 ₂ are arranged as partof a color print pen 90, and fluid ejection die 20 ₃ is arranged as apart of a monochromatic print pen 92.

In one example, each fluidic ejection die 20 ₀ to 20 ₃ receives datafrom a corresponding one of data pads 44 ₀ to 44 ₃, and each share CLKPad 42, FIRE pad 46, MODE pad 48, and SENSE pad 50. In examples, each ofthe memory arrays 28 ₀, 28 ₁, 28 ₂ and 28 ₃ may be separately accessedduring a memory access operation. In other examples, any combination ofmemory arrays 28 ₀, 28 ₁, 28 ₂ and 28 ₃ may be simultaneously accessedduring a memory access operation. For example, memory elements from eachof the memory arrays 28 ₀, 28 ₁, 28 ₂ and 28 ₃ may be simultaneouslyaccessed (e.g., a read operation) via sense line 52, such as by printer60.

Memory circuit 30 is connected to CLK pad 42, FIRE pad 46, MODE pad 48,and SENSE pad 50, and is connected to each of data pads 44 ₀ to 44 ₃ soas to be connected in parallel with each of the fluidic ejection dies 20₀, 20 ₁, 20 ₂ and 20 ₃. In examples, memory circuit 30 may serve as areplacement memory for any combination of memory arrays 28 ₀, 28 ₁, 28 ₂and 28 ₃. For example, in one case, memory circuit 30 may serve as areplacement memory for memory array 24 ₁, whereas in another example,memory circuit 30 may serve as a replacement for each of the memoryarrays 28 ₀, 28 ₁, 28 ₂ and 28 ₃.

In one example, memory circuit 30 may serve as supplemental memory for afluidic ejection circuit 20. In such case, for memory access operations,memory elements 29 of the fluidic ejection circuit 20 and memory values36 of memory circuit 30 may be separately identified using columnselection bits in the configuration data of FPG data packetscommunicating memory select data. For example, fluidic ejection circuit20 ₃ of monochromatic print pen 92 may include a memory array 28 ₃having a number of columns of memory elements 29, such as three columns,for instance. In such case, the columns of memory elements of fluidicejection circuit 20 ₃ may be identified by column selection bits ofconfiguration data of the FPG data packet as columns 1-3, and additionalcolumns of memory values 36 of memory component 34 acting assupplemental memory may be identified as additional columns beginningwith column 4.

In one example, similar to that described above with respect to FIG. 3,memory circuit 30 monitors operating signals on the number I/O pads 40to detect a memory access sequence for any of the memory arrays 28 ₀, 28₁, 28 ₂ and 28 ₃ for which memory circuit 30 serves as a replacementmemory.

In one example, when memory circuit 30 serves as a replacement memoryfor less than all of the fluidic ejection dies 20 ₀, 20 ₁, 20 ₂ and 20 ₃of print component 10, memory elements 29 of fluidic ejection dies 20for which memory circuit 30 does not serve as a replacement memory areunable to read in parallel with memory elements of fluidic ejection dies20 for which memory circuit serves as a replacement memory.

FIG. 5 is a block and schematic diagram generally illustrating memorycircuit 30 connected to print component 10, according to one example,where portions of print component 10 are also shown. As will bedescribed in greater detail below, according to the example of FIG. 5,memory circuit 30 is connected in parallel with fluidic ejection device20 to SENSE pad 50 during memory access operations. In example,according to the illustration of FIG. 5, memory circuit 30 may serve asa replacement memory for the array 28 of memory elements 29 of fluidicejection circuit 20 (where one or more memory elements 29 may bedefective).

In one example, activation logic 84 of fluid ejection circuit 20includes a read enable switch 100, a column activation switch 102controlled via an AND-gate 103, and a memory element select switch 104controlled via an AND-gate 106. According to one example, as describedabove, during a read operation, fluidic ejection circuit 20 receives afire pulse group including configuration data (e.g., in a head and/ortail portion), and memory select data (e.g., in a body portion). In oneexample, the configuration data includes a column select bit and addressdata. The column select bit indicates a particular column of memoryelements 29 being accessed when memory array 28 includes more than onecolumn of memory elements, such as columns 28 ₁ and 28 ₂ in FIG. 3. Theaddress data is decoded by address decoder 82 and provided to activationcircuit 84. In one example, the select data includes a number of memoryselect bits, where each select data bit corresponds to a differentprimitive (P₀ to P_(M)) of the column of memory elements 29, where aselect bit which is set (e.g., has a value of “1”) enables memoryelements 29 of the column 28 to be accessed for reading (or writing).

Additionally, as part of the read operation protocol, memoryconfiguration register 88 is loaded with a column enable bit and a readenable bit. The read enable bit of memory configuration register 88turns on read enable switch 100. When FIRE is raised, the column enablebit of configuration register 88 together with the column select bit ofthe configuration data of the fire pulse group cause AND-gate 103 toturn on column activation switch 102 for the selected column, and theselect data and address (via address decoder 86) of the fire pulsegroup, and FIRE signal together cause AND-gate 106 to turn on memoryelement select switch 104, thereby connecting memory element 29 to senseline 52. It is noted that, in some examples, a column select bit may notbe included as part of the fire pulse group configuration data whenfluidic ejection circuit 20 includes a single column of memory elements.

Once connected to sense line 52, memory element 29 provides an analogoutput signal in response to an analog sense signal on sense line 52,where a value of the analog output signal depends on a program state ofmemory element (where such program state may be defective). In oneexample, as described above, memory element 29 may have a relativelyhigher electrical resistance when having a non-programmed state (e.g., avalue of “0”) than when having a programmed state (e.g., a value of“1”). Accordingly, when the analog sense signal is a fixed analogcurrent (a so-called “forced current mode”), an analog output voltageprovided by memory element 29 will have a relatively higher voltagelevel when memory element 29 has a non-programmed state, and arelatively lower voltage level when memory element 29 has a programmedstate. Likewise, when the analog sense signal is a fixed voltage (aso-called “forced voltage mode”), an analog output current provided bymemory element 29 will have a relatively lower current level when memoryelement 29 has a non-programmed state, and a relatively higher currentlevel when memory element 29 has a programmed state.

It is noted that during a write operation, read enable switch 100 ismaintained in an open position to disconnect memory element 29 fromsense line 52, while column enable switch 102 and memory element selectswitch 104 are closed. The write enable bit of memory configurationregister connects voltage regulator 90 to memory element 29 to apply aprogram voltage thereto.

Control circuit 32 of memory circuit 30, according to one example,includes control logic 120, a first voltage-controlled current source122 operating as a current supply to a node 128, and a second voltagecontrolled current source operating as a current sink from node 128,with node 128 being connected to sense line 52 at second SENSE pad 50 ₁via a control line 129. In the example of FIG. 4, during a memory accessoperation, memory circuit 20 is connected to sense line 152 in parallelwith fluidic ejection circuit 20 at second SENSE pad 50 ₁.

In one example, memory circuit 30 is connected in parallel with fluidejection circuit 20 to I/O pads 40 via an overlay wiring substrate 160,which is described in greater detail below (e.g., see FIG. 6A). In oneexample, wiring substrate 160 includes a pair of I/O pads for eachsignal path, with the signal path routed through overlay wiringsubstrate 160 to print component 10 from the first I/O pad of the pairto the second I/O pad of the pair. For example, wiring substrate 160includes a pair of CLK pads 42 and 42 ₁, a pair of DATA Pads 44 and 44₁, a pair of FIRE Pads 46 and 46 ₁, a pair of MODE Pads 48 and 48 ₁, anda pair of SENSE Pads 50 and 50 ₁. In one example, in each case, thefirst pad of the pair of pads connects to the incoming signal line, andthe second pad of the pair of pads connects the outgoing signal line toprint component 10.

In one example, overlay wiring substrate 160 further includes a senseresistor 150 connected in series with sense line 52, where control logic120 monitors a voltage on high and low side terminals 152 and 154 ofsense resistor 150. In other examples, sense resistor 150 may bearranged as part of control circuit 32 (e.g., see FIG. 10).

Although illustrated as being connected to the signal paths and printcomponent 10 via wiring substrate 160, any number of otherimplementations may be employed to provide such connection. Forinstance, in one example, the functionality of wiring substrate 160 mayintegrated within memory circuit 30.

Memory component 34 includes a number of memory values 36. In oneexample, each memory value 36 corresponds to a different one of thememory elements 29 of fluidic ejection circuit 20. However, whereas oneor more memory elements 29 of fluidic ejection circuit 20 may bedefective and store incorrect values, each of the memory values 36 ofmemory component 34 represents a correct memory value. It is noted thatin examples, memory component 34 may include memory values 36 inaddition to memory values 36 corresponding to memory elements 29.

In one example, control circuit 32 monitors the operating signals beingcommunicated to fluidic ejection circuit 20 on I/O pads 40, such as fromprinter 60. In one example, upon detecting operating signalsrepresenting a memory access sequence indicative of a read operation ofmemory element 29, control logic 120 monitors the voltage on high-sideterminal 152 (or low-side terminal 154) of sense resistor 150 todetermine whether the read operation is being performed in a forcedcurrent mode or a forced voltage mode. If a forced current mode is beingemployed, the voltage level on high-side terminal 152 will rise (e.g., alinear rise) for a time period following FIRE pad 46 being raised assense line 52 charges. If a forced voltage mode is being employed, thevoltage on high-side terminal 152 will remain relatively steady at thefixed voltage level of the input sense signal.

In one example, upon detecting a read operation, control logic 120 readsthe memory value 36 corresponding to the memory element 29 identified asbeing accessed by the read operation. Based on the memory value 36,control logic 120 is able to determine an expected output responsevoltage level that should be present on SENSE pad 50 during a forcedcurrent mode read operation, and an expected output response currentlevel that should be present on SENSE pad 50 during forced voltage moderead operation via a feedback loop formed with sense resistor 150.

Since memory circuit 30 is connected in parallel with fluidic ejectioncircuit 20 to sense line 52, during a read operation, in response to theanalog sense signal being forced on sense line 52, an analog outputresponse signal (e.g., a voltage or a current) from memory element 29 ispresent at second SENSE pad 50 ₁. In one example, control logic 120adjusts the voltage controlled current sources 122 and 124 to providecurrent to second SENSE pad 50 ₁ or to draw current from second sensepad 50 ₁ so that the combination of the output response from memoryelement 29 of fluidic ejection circuit 20 and the output response ofcontrol circuit 32 at second SENSE Pad 50 produces the expected analogoutput response level (voltage or current) at SENSE pad 50.

In one example, when in forced current mode, control logic 120 monitorsthe voltage at high-side terminal 152 of sense resistor 150 and adjustsvoltage controlled current sources 122 and 124 to adjust an amount ofcurrent provided to second SENSE pad 50 ₁ (either providing current tosecond SENSE pad 50 ₁ or drawing current from second SENSE pad 50 ₁) sothat the combined response of memory circuit 30 and fluidic ejectioncircuit 20 provides the expected output response voltage level at SENSEpad 50.

Similarly, in one example, when in forced voltage mode, control logicmonitors the voltage across sensor resistor 150 via high-side andlow-side terminals 152 and 154 to determine the output response currentlevel at SENSE pad 50. Control circuit 120 then adjusts voltagecontrolled current sources 122 and 124 to adjust the amount of currentprovided to second SENSE pad 50 ₁ (either providing current to secondSENSE pad 50 ₁ or drawing current from second SENSE pad 50 ₁) so thatthe combined response of memory circuit 30 and fluidic ejection circuit20 provides the expected output response current level at SENSE pad 50.

By controlling voltage-controlled current sources 122 and 124 to providean expected analog output response value at SENSE pad 50 based on thecorrect memory values for fluidic ejection circuit 20 as stored asmemory values 36 by memory component 34, memory circuit 30 is able toreplace a defective memory array 28 on fluidic ejection circuit 20 sothat print component 10 is able to remain operational, thereby reducingthe number of defective print components during manufacturing.Additionally, by connecting memory circuit 30 in parallel with fluidicejection circuit to I/O pads 40, sensors 70 of fluidic ejection circuit20 remain accessible at all times for monitoring via SENSE pad 50, suchas by printer 60.

FIG. 6A is a cross-sectional view illustrating portions of an overlaywiring substrate 160 for connecting memory circuit 20 to I/O terminals40. In particular, FIG. 6A represents a cross-sectional view extendingthrough SENSE pad 50 of FIG. 5, where memory circuit 30 is coupled inparallel with fluidic ejection circuit 20 to sense pad 50. In oneexample, overlay wiring substrate 160 includes a flexible substrate 162having a first surface 163 and an opposing second surface 164. Memorycircuit 30 and SENSE pad 50 are disposed on first surface 163, with aconductive trace representing sense line 52 connecting SENSE pad 50 tomemory circuit 30. In one example, as illustrated, sense resistor 150 indisposed in series with sense line 52 between SENSE pad 50 and memorycircuit 30. In one example, a conductive via 166 extends from sense line52 at first surface 163 through flexible substrate 163 to second SENSEpad 50 ₁ on second surface 164.

Print component 10 includes a substrate 168 on which fluidic ejectioncircuit 20 is mounted, and includes a SENSE pad 50 ₂ coupled to fluidicejection circuit 20 by a sense line 52 ₁. When flexible wiring substrate160 is coupled to print component 10, as indicated by the directionalarrow 169, second SENSE pad 50 ₁ aligns with SENSE pad 50 ₂ to connectsense line 52 to SENSE pad 50 ₂ between sense resistor 150 and memorycircuit 30.

FIG. 6B is a block diagram generally illustrating a cross-sectional viewof overlay wiring substrate 160 showing connections of I/O pads 40 otherthan SENSE pad 50, for example, such as MODE pad 48, for instance. Asillustrated, MODE pad 48 is disposed on top surface 163 of substrate162. A via 167 extends through substrate 162 to connect first MODE pad48 to second MODE pad 48 ₁ on second surface 164. When flexible wiringsubstrate 160 is coupled to print component 10, MODE pad 48 ₁ alignswith MODE pad 48 ₂ to connect MODE pad 48 to fluidic ejection circuit20.

FIG. 7 is a block and schematic diagram generally illustrating memorycircuit 10, according to one example. Portions of print component 10 arealso generally illustrated. The example of FIG. 7 is similar to that ofFIG. 5, where memory circuit 30 is connected in parallel with fluidicejection device 20 to SENSE pad 50 during memory access operations.However, in the example of FIG. 7, control circuit 32 of memory circuit30 includes an op-amp 170 and a controllable voltage source 172 in lieuof voltage-controlled current sources 122 and 124.

A first input of op-amp 170 is connected to a reference potential (e.g.,ground) via controllable voltage source 172. A second input and anoutput of op-amp 170 are connected to node 128, with node 128 beingconnected to SENSE pad 50 ₁ via line 129.

In one example, during a memory read operation, when in forced currentmode, control logic 120 monitors the voltage at high-side terminal 152of sense resistor 150 and adjusts the output voltage of op-amp 170 byadjusting the voltage level of controllable voltage source 172 (wherethe output voltage approximately follows that of controllable voltagesource 172), so as to adjust an amount of current provided to secondSENSE pad 50 ₁ (either providing current to second SENSE pad 50 ₁ ordrawing current from second SENSE pad 50 ₁) so that the combinedresponse of memory circuit 30 and fluidic ejection circuit 20 providesthe expected output response voltage level at SENSE pad 50.

Similarly, in one example, when in forced voltage mode, control logicmonitors the voltage across sensor resistor 150 via high-side andlow-side terminals 152 and 154 to determine the output response currentlevel at SENSE pad 50. Control circuit 120 then adjusts the outputvoltage of op-amp 170 by adjusting the voltage level of controllablevoltage source 172 (where the output voltage approximately follows thatof controllable voltage source 172), so as to adjust the amount ofcurrent provided to second SENSE pad 50 ₁ (either providing current tosecond SENSE pad 50 ₁ or drawing current from second SENSE pad 50 ₁) sothat the combined response of memory circuit 30 and fluidic ejectioncircuit 20 provides the expected output response current level at SENSEpad 50.

FIG. 8 is a block and schematic diagram of memory circuit 30 for printcomponent 10, according to one example. The example of FIG. 8 is similarto that of FIG. 5, where memory circuit 30 is connected in parallel withfluidic ejection device 20 to SENSE pad 50 during memory accessoperations. However, in the example of FIG. 8, control circuit 32 ofmemory circuit 30 includes a number of resistors 180-183 which may beconnected to form an adjustable voltage divider between voltage sourceVCC and a reference voltage (e.g., ground) in lieu of voltage-controlledcurrent sources 122 and 124.

In example, a source resistor 180 is connected between voltage sourceVCC and node 128. Sink resistors 181-183 are connected in parallel withone another between node 128 and a reference voltage (e.g., ground) viarespective switches 184-186. It is noted that a number of resistorsdifferent from that illustrated in FIG. 8 may be employed by controlcircuit 32.

In one example, during a memory read operation, when in forced currentmode, control logic 120 monitors the voltage at high-side terminal 152of sense resistor 150 and adjusts the number of sink resistors 181-183which are connected between node 128 and ground via control of switches184-186 to adjust an amount of current provided to second SENSE pad 50 ₁so that the combined response of memory circuit 30 and fluidic ejectioncircuit 20 provides the expected output response voltage level at SENSEpad 50.

Similarly, in one example, when in forced voltage mode, control logicmonitors the voltage across sensor resistor 150 via high-side andlow-side terminals 152 and 154 to determine the output response currentlevel at SENSE pad 50. Control circuit 120 then adjusts the number ofsink resistors 181-183 which are connected between node 128 and groundvia control of switches 184-186 to adjust the amount of current providedto second SENSE pad 50 ₁ (either providing current to second SENSE pad50 ₁ or drawing current from second SENSE pad 50 ₁) so that the combinedresponse of memory circuit 30 and fluidic ejection circuit 20 providesthe expected output response current level at SENSE pad 50.

FIG. 9 is a block and schematic diagram generally illustrating memorycircuit 30, according to one example. Memory circuit 30 includes aplurality of I/O pads 40, including an analog pad 50, to connect to aplurality of signal paths 41 communicating operating signals to printcomponent 10. In one example, a controllable selector 190 is connectedin-line with one of the signal paths 41 via the I/O pads 40, with thecontrollable selector 190 controllable to open the corresponding signalline to the print component 10 (to interrupt or break the connection toprint component 10). In one example, in response to a sequence ofoperating signals received by I/O pads 40 representing a memory read,control circuit 32 opens controllable selector 190 to break the signalpath to print component 10 to block a memory read of print component 10,and provides an analog signal to analog pad 50 to provide an analogelectrical value at analog pad 50 representing stored memory values 36selected by the memory read. By breaking the signal path during a memoryread, print component 10 is unable to provide an analog signal to analogpad 50 during memory read operations. In examples, print component 10 isenabled to provide an analog signal pad 50 during non-memory readfunctions which access analog pad 50, such as a read of an analogcomponent. In examples, such analog component may be a sense circuit(e.g., a thermal sensor).

FIG. 10 is a block and schematic diagram illustrating memory circuit 30,according to one example of the present disclosure, where controllableselector 190 is a controllable switch 190. In the example of FIG. 10,I/O pads 40 include a first analog pad 50 and a second analog pad 50 ₁connected to an analog signal line 52, where controllable switch 90 isconnect between analog pads 50 and 50 ₁ so as to be connected in-linewith analog signal line 52. In one example, as illustrated, controlcircuit 32 further includes a second controllable switch 192 connectedto first analog pad 50. The example of FIG. 10 is similar to that ofFIG. 5, except controllable selector switches 190 and 192 enable controlcircuit 32 to selectively couple and decouple memory circuit 30 andfluidic ejection circuit 20 from select line 52 such that, in oneexample, memory circuit 30 is not coupled in parallel with fluidicejection circuit 20 during a memory access operation. Additionally,according to one example, sense resistor 150 along with high-side andlow-side terminals 152 and 154 are disposed within memory circuit 32.

In one example, when control logic 120 identifies a non-memory accessoperation, control logic opens controllable selector switch 190 todisconnect voltage-controlled current sources 122 and 124 from senseline 52, and close selector switch 192 to connect fluid ejection circuit20 to sense line 52, to enable monitoring of sensors 70 (see FIG. 3),such as by printer 60, without potential for interference in outputsignals of sensors 70 by control circuit 32.

In one example, when control logic 120 identifies a memory accessoperation, control logic may close selector switch 192 to connect node128 and voltage-controlled current sources 122 and 124 to sense line 52,and open selector switch 190 to disconnect fluidic ejection circuit 20from sense line 52, so that fluidic ejection circuit 20 is no longerconnected in parallel with control circuit 32 to second SENSE pad 50 ₁,so that fluidic ejection circuit 20 is blocked from responding to amemory read operation. Control circuit 32 can then adjust voltagecontrolled current sources 122 and 124 to provide the expected analogvoltage response at SENSE pad 50, as described above with respect toFIG. 5, but without the contribution of an analog output response signalfrom fluidic ejection circuit 20. By disconnecting fluidic ejectioncircuit 20 from sense line 52 during memory access operations, potentialcontamination from defective memory elements 29 in the analog outputresponse signal at SENSE pad 50 can be eliminated.

In other examples, controllable selector switch 190 may be connected ina similar fashion so as to be in-line with a fire signal path via FIREpad, such that a fire signal is blocked from fluidic ejection circuit 20during a memory read operation so that fluidic ejection circuit 20 isunable to respond to such memory read operation. In another example,controllable selector 190 may be a multiplexer coupled in-line withsense line 52 (or analog path 52), where the control circuit 32 operatesthe multiplexer operates to disconnect sense line 52 from fluidicejection circuit 20 during a memory read, and otherwise operates toconnect sense line 52 to fluid ejection circuit 20, such as duringnon-memory read operations which access analog sense pad 50 and senseline 52.

It is noted that the configurations of control circuit 32 described byFIGS. 6 and 7, and any number of other suitable control configurations,may be employed in the example print component 10 of FIG. 10.

FIG. 11 is a cross-sectional view illustrating portions of overlaywiring substrate 160 for connecting memory circuit 30 to I/O terminals40 as illustrated by FIG. 10, according to one example. In particular,FIG. 11 represents a cross-sectional view extending through SENSE pad50. In one example, memory circuit 30 and SENSE pad 50 are disposed onfirst surface 163 of flexible substrate 162, with a conductive tracerepresenting sense line 52 connecting SENSE pad 50 to memory circuit 30.According to one example, sense resistor 150 and selector switches 190and 192 are disposed internally to memory circuit 30. A conductive via167 extends through flexible substrate 162, with memory circuit 30 beingelectrically connected to a SENSE pad 50 ₂ on second surface 164 offlexible substrate 162 with conductive traces 52 ₂ and 52 ₃(representing portions of sense line 52) by way of via 167. Whenflexible wiring substrate 160 is coupled to print component 10, asindicated by arrow 169, sense pad 50 ₂ aligns with sense pad 50 ₁ suchthat SENSE pad 50 is coupled to fluidic ejection circuit 20 via selectorswitch 192 in memory circuit 30.

FIG. 12 is a block and schematic diagram generally illustrating memorycircuit 30, according to one example. Memory circuit 30 includes aplurality of I/O pads 40, including first and second analog pads 1 and2, indicated at 50 and 50 ₁, to connect a plurality of signal paths 41to print component 10, including an analog signal path 52 connected toAnalog Pads 50 and 50 ₁. In one example, the first analog pad 50 iselectrically isolated from the second analog pad 50 ₁ to break theanalog signal path to print component 10. In response to a sequence ofoperating signals on I/O pads 40 representing a memory read, controlcircuit 32 provides an analog signal to first analog pad 50 to providean analog electrical value at first analog pad 50 representing storedmemory values 36 selected by the memory read.

By breaking the analog signal path 52 during a memory read, printcomponent 10 is disconnected from analog signal path 52 during memoryread operations. As will be described in greater detail below, inaddition to providing memory values 36 corresponding to memory elementsof print component 10, memory values 36 may represent values for otherfunctions that access print component 10 via analog signal path 52, suchsensor read commands (e.g., to read thermal sensors).

FIG. 13 is a block and schematic diagram of memory circuit 30, accordingto one example, and generally illustrating portions of print component10. The example of FIG. 13 is similar to that of FIG. 10, but ratherthan including a selector switch (e.g., selector switch 192) toselectively control connection of fluidic ejection circuit 30 to senseline 52, fluidic ejection circuit 30 is physically decoupled from senseline 52. In one example, with reference to FIG. 14 below, overlay wiringsubstrate 160 is arranged to connect memory circuit 30 to select line 52and to connect memory circuit 30 to I/O pads 42-48 in parallel withfluidic ejection circuit 20, while disconnecting fluidic ejectioncircuit 20 from SENSE pad 50.

In one example, upon identifying a memory access operation of fluidicejection circuit 20 on I/O pads 40, control logic operates as describedby FIGS. 4 and 8 above to update memory values 36 in view of writeoperations, and to provide expected analog output responses at SENSE pad50 in view of read commands.

However, as described earlier, SENSE pad 50, via sense line 52, is alsoemployed to read sensors 70 (see FIG. 3), such as thermal sensors andcrack sensors, for example. Such sensors are read in a fashion similarto that of memory elements 29 of fluid ejection circuit 20, where ananalog sense signal is applied to a sensor and an analog response signalis indicative of a sensed temperature in the case of a temperaturesensor, and indicative of a presence or absence of a crack in the caseof a crack sensor. In one example, in the case of a temperature sensor,an analog output signal representative of a sensed temperature within adesignated operating temperature range is indicative of proper operationof fluidic ejection circuit 20, while a sensed temperature outside ofthe designated operating temperature range may indicate improperoperation of fluidic ejection circuit 20 (e.g., overheating). Similarly,in the case of a crack sensor, an analog signal representative of senseda resistance below a designated threshold value may indicate the absenceof a crack in fluidic ejection circuit 20, while a sensed resistanceabove the designated threshold value may indicate the presence of acrack in fluidic ejection circuit 20.

In view of the above, in one example, in addition to memory component 34including memory values 36 corresponding to memory elements 29 offluidic ejection circuit 20, memory component 34 includes a memory value36 corresponding to each of the sensors 70 of fluidic ejection circuit20. In one example, the memory value 36 represents a value of an analogoutput signal to be provided by control circuit 32 at SENSE pad 50 inresponse to a read operation of the sensor 70 corresponding to thememory value 36 being recognized on I/O pads 40 by memory circuit 30. Inone example, control logic 120 controls voltage controlled currentsources 122 and 124 to provide an analog output signal at SENSE pad 50as indicated by the corresponding memory value 36.

In view of the above, as described above, with SENSE pad 50 physicallydecoupled from fluidic ejection circuit 20, memory circuit 30 emulatesanalog output signal responses for memory elements 29 and sensors 70 offluidic ejection circuit 20 based on memory values 36 stored by memorycomponent 34. According to one example, memory circuit 30 of FIG. 13 maybe mounted to print component 10 via flexible wiring substrate 160 toreplace defective memory elements 26 and defective sensors 70 tomaintain operation of print component 10.

In one example, memory circuit 30 of FIG. 13 may be temporarily mountedto print component 10 via flexible wiring substrate 160 and serve as adiagnostic circuit for testing a response to an external circuit, suchas printer 60, to simulated conditions on fluidic ejection circuit 20.For example, memory values 36 corresponding to sensors 70 comprisingtemperature sensors may have values corresponding to temperature valuesoutside of a desired operating temperature value range to test theresponse of printer 60 to such conditions. In other examples, memoryvalues corresponding to sensors 70 comprising crack sensors may havevalues corresponding to a resistance value above a threshold valueindicative of a presence of a crack to test the response of printer 60to such conditions. Any number of other conditions may be simulated bymemory circuit 30, thereby enabling a response of printer 60 tosimulated operating conditions to be tested without access to fluidicejection circuit 20 via sense line 52. In one example, after diagnostichas been completed, memory circuit 30 and flexible wiring circuit 160may be removed from print component 10.

FIG. 14 is a cross-sectional view illustrating portions of overlaywiring substrate 160 for connecting memory circuit 30 to I/O terminals40 as illustrated by FIG. 13, according to one example. In particular,FIG. 14 represents a cross-sectional view extending through SENSE pad50. In one example, memory circuit 30 and SENSE pad 50 are disposed onfirst surface 163 of flexible substrate 162, with a conductive tracerepresenting sense line 52 connecting SENSE pad 50 to memory circuit 30.A second SENSE pad 50 ₁ is disposed on second surface 164 of substrate162, and is electrically isolated from SENSE pad 50, sense line 52, andmemory circuit 30. A SENSE pad 50 ₂ is disposed on print componentsubstrate 168 and is connected by conductive trace 52 ₁ to fluidicejection circuit 20. When flexible wiring substrate 160 is mounted toprint component 10 (as indicated by direction arrow 169), SENSE pad 50 ₁aligns with and contacts SENSE pad 50 ₂. Since SENSE pad 50 ₁ iselectrically isolated form SENSE pad 50, no electrical contact is madebetween SENSE pad 50 and underlying pad 50 ₁, such that the connectionbetween fluidic ejection circuit 20 and SENSE pad 50 is broken.

FIG. 15 is a block diagram illustrating one example of a fluid ejectionsystem 200. Fluid ejection system 200 includes a fluid ejectionassembly, such as printhead assembly 204, and a fluid supply assembly,such as ink supply assembly 216. In the illustrated example, fluidejection system 200 also includes a service station assembly 208, acarriage assembly 222, a print media transport assembly 226, and anelectronic controller 230. While the following description providesexamples of systems and assemblies for fluid handling with regard toink, the disclosed systems and assemblies are also applicable to thehandling of fluids other than ink.

Printhead assembly 204 includes at least one printhead 212 which ejectsdrops of ink or fluid through a plurality of orifices or nozzles 214,where printhead 212 may be implemented, in one example, as fluidicejection circuit 20, with fluid actuators (FAs) 26 implemented asnozzles 214, as previously described herein by FIG. 3, for instance. Inone example, the drops are directed toward a medium, such as print media232, so as to print onto print media 232. In one example, print media232 includes any type of suitable sheet material, such as paper, cardstock, transparencies, Mylar, fabric, and the like. In another example,print media 232 includes media for three-dimensional (3D) printing, suchas a powder bed, or media for bioprinting and/or drug discovery testing,such as a reservoir or container. In one example, nozzles 214 arearranged in at least one column or array such that properly sequencedejection of ink from nozzles 214 causes characters, symbols, and/orother graphics or images to be printed upon print media 232 as printheadassembly 204 and print media 232 are moved relative to each other.

Ink supply assembly 216 supplies ink to printhead assembly 204 andincludes a reservoir 218 for storing ink. As such, in one example, inkflows from reservoir 218 to printhead assembly 204. In one example,printhead assembly 204 and ink supply assembly 216 are housed togetherin an inkjet or fluid-jet print cartridge or pen. In another example,ink supply assembly 216 is separate from printhead assembly 204 andsupplies ink to printhead assembly 204 through an interface connection220, such as a supply tube and/or valve.

Carriage assembly 222 positions printhead assembly 204 relative to printmedia transport assembly 226, and print media transport assembly 226positions print media 232 relative to printhead assembly 204. Thus, aprint zone 234 is defined adjacent to nozzles 214 in an area betweenprinthead assembly 204 and print media 232. In one example, printheadassembly 204 is a scanning type printhead assembly such that carriageassembly 222 moves printhead assembly 204 relative to print mediatransport assembly 226. In another example, printhead assembly 204 is anon-scanning type printhead assembly such that carriage assembly 222fixes printhead assembly 204 at a prescribed position relative to printmedia transport assembly 226.

Service station assembly 208 provides for spitting, wiping, capping,and/or priming of printhead assembly 204 to maintain the functionalityof printhead assembly 204 and, more specifically, nozzles 214. Forexample, service station assembly 208 may include a rubber blade orwiper which is periodically passed over printhead assembly 204 to wipeand clean nozzles 214 of excess ink. In addition, service stationassembly 208 may include a cap that covers printhead assembly 204 toprotect nozzles 214 from drying out during periods of non-use. Inaddition, service station assembly 208 may include a spittoon into whichprinthead assembly 204 ejects ink during spits to ensure that reservoir218 maintains an appropriate level of pressure and fluidity, and toensure that nozzles 214 do not clog or weep. Functions of servicestation assembly 208 may include relative motion between service stationassembly 208 and printhead assembly 204.

Electronic controller 230 communicates with printhead assembly 204through a communication path 206, service station assembly 208 through acommunication path 210, carriage assembly 222 through a communicationpath 224, and print media transport assembly 226 through a communicationpath 228. In one example, when printhead assembly 204 is mounted incarriage assembly 222, electronic controller 230 and printhead assembly204 may communicate via carriage assembly 222 through a communicationpath 20 ₂. Electronic controller 230 may also communicate with inksupply assembly 216 such that, in one implementation, a new (or used)ink supply may be detected.

Electronic controller 230 receives data 236 from a host system, such asa computer, and may include memory for temporarily storing data 236.Data 236 may be sent to fluid ejection system 200 along an electronic,infrared, optical or other information transfer path. Data 236represent, for example, a document and/or file to be printed. As such,data 236 form a print job for fluid ejection system 200 and includes atleast one print job command and/or command parameter.

In one example, electronic controller 230 provides control of printheadassembly 204 including timing control for ejection of ink drops fromnozzles 214. As such, electronic controller 230 defines a pattern ofejected ink drops which form characters, symbols, and/or other graphicsor images on print media 232. Timing control and, therefore, the patternof ejected ink drops, is determined by the print job commands and/orcommand parameters. In one example, logic and drive circuitry forming aportion of electronic controller 230 is located on printhead assembly204. In another example, logic and drive circuitry forming a portion ofelectronic controller 230 is located off printhead assembly 204. Inanother example, logic and drive circuitry forming a portion ofelectronic controller 230 is located off printhead assembly 204. In oneexample, electronic controller 230 may provide operating signals via I/Opads 40 to print component 10, such as illustrated by FIG. 1.

Although specific examples have been illustrated and described herein, avariety of alternate and/or equivalent implementations may besubstituted for the specific examples shown and described withoutdeparting from the scope of the present disclosure. This application isintended to cover any adaptations or variations of the specific examplesdiscussed herein. Therefore, it is intended that this disclosure belimited only by the claims and the equivalents thereof.

The invention claimed is:
 1. A memory circuit separate from a fluidejection die of a print component, the memory circuit comprising: aplurality of I/O pads to connect to a plurality of I/O signal pathswhich communicate operating signals between the print component and aprinter, the plurality of I/O pads including an analog pad to receiveand provide analog signals; a memory component to store memory valuesassociated with the print component; and a control circuit connected tothe I/O pads, in response to detecting a sequence of operating signalson the I/O pads representing a memory read, to provide an analog signalto the analog pad to provide as output to the printer an analogelectrical value at the analog pad representing stored memory valuesselected by the memory read.
 2. The memory circuit of claim 1, inresponse to a sequence of operating signals on the I/O pads representinga memory write, the control circuit to update the stored memory elementsidentified by the memory write.
 3. The memory circuit of claim 1, theanalog pad being an analog sense pad.
 4. The memory circuit of claim 1,the analog pad connected to an analog sense circuit.
 5. The memorycircuit of claim 1, the memory values of the memory circuit tosupplement an array of memory elements of the print component.
 6. Thememory circuit of claim 1, the memory component and control circuitbeing on a same die.
 7. The memory circuit of claim 1, the memorycomponent comprising an array of memory cells storing the memory values.8. The memory circuit of claim 1, the memory component comprising alook-up table of memory values.
 9. The memory circuit of claim 1, thememory circuit to be coupled in parallel with the print component to thesignal paths via the I/O pads.
 10. A memory circuit for a printcomponent comprising: a plurality of I/O pads to connect to a pluralityof I/O signal paths which communicate operating signals with the printcomponent, the plurality of I/O pads including an analog pad to connectto, and to receive and provide analog signals on, a signal path whichcommunicates analog operating signals of the print component; a memorycomponent to store memory values associated with the print component;and a control circuit, in response to a sequence of operating signals onthe I/O pads representing a memory read, to provide an analog signal tothe analog pad to provide an analog electrical value at the analog padrepresenting stored memory values selected by the memory read, and inresponse to a sequence of operating signals on the I/O pads representingnon-memory read functions which access the analog pad, the controlcircuit to provide an analog signal to the analog pad to provide ananalog electrical value at the analog pad representing stored memoryvalues corresponding to the non-memory read functions.
 11. The memorycircuit of claim 10, the non-memory read function comprising a read ofat least one analog component.
 12. The memory circuit of claim 11, theat least one analog component comprising at least one sense circuit. 13.A print component comprising: a number of I/O pads to communicateoperating signals for controlling operation of the print component, thenumber of I/O pads including an analog pad to connect to and to receiveand provide analog signals on a signal path which communicates analogoperating signals of the print component, the I/O pads to connect to afluid ejection die; a memory circuit coupled to the I/O pads, the memorycircuit including: a memory component to store memory values associatedwith the print component; and a control circuit, in response todetecting a sequence of operating signals being communicated by the I/Opads representing a memory read of a memory of the fluid ejection die,to provide an analog signal on the analog pad representing the storedmemory values corresponding to the memory read, such that the memorycircuit is configured to at least partially replace or substitute amemory on the fluid ejection die.
 14. The print component of claim 13,in response to a sequence of operating signals being communicated by theI/O pads representing a memory write, the control circuit to update thestored memory values identified by the memory write.
 15. The printcomponent of claim 13, the analog pad being an analog sense pad.
 16. Theprint component of claim 13, the analog pad connected to an analog sensecircuit.
 17. The print component of claim 13, the fluidic ejectioncircuit including an array of memory elements, the memory values of thememory circuit to supplement the array of memory elements.
 18. The printcomponent of claim 13, the fluidic circuit and the memory circuit beingseparate dies.
 19. The print component of claim 13, the memory componentcomprising an array of memory cells storing the memory values.
 20. Theprint component of claim 13 the memory component comprising a lookuptable of the memory values.
 21. The print component of claim 13, thememory circuit coupled to the I/O pads in parallel with the fluidicejection circuit.
 22. A print component comprising: a number of I/O padsto communicate operating signals for controlling operation of the printcomponent, the number of I/O pads including an analog pad to connect toand to receive and provide analog signals on a signal path whichcommunicates analog operating signals of the print component, the I/Opads to connect to a fluid ejection die; and a memory circuit coupled tothe I/O pads, the memory circuit including: a memory component to storememory values associated with the print component; and a control circuitto: in response to a sequence of operating signals being communicated bythe I/O pads representing a memory read, provide an analog signal on theanalog pad representing the stored memory values corresponding to thememory read, and in response to a sequences of operating signals on theI/O pads representing non-memory read functions which access the analogpad, the control circuit to provide an analog signal to the analog padto provide an analog electrical value at the analog pad representingstored memory values corresponding to the non-memory read functions sothat the memory component is configured to at least partially replaceand/or substitute a memory on the fluid ejection die.
 23. A printcomponent comprising: a plurality of fluidic ejection dies, each dieincluding: an array of fluid actuators; and an array of memory elements,each memory element to store a data bit representing data associatedwith the print component; a number of I/O pads to communicate operatingsignals between the print component and a printer, the I/O padsconnected to the fluidic ejection dies and including an analog sense padconnected in parallel with each of the fluidic ejection dies, the analogpad to receive and provide analog signals; and a memory circuit coupledto the I/O pads, the memory circuit separate from the fluid ejectiondies and including: a memory component to store memory values associatedwith the print component; and a control circuit, in response todetecting a sequence of operating signals being communicated by the I/Opads representing a memory read of memory elements of the fluidicejection dies, to provide an analog signal at the analog sense padrepresenting stored memory values corresponding to memory elementsidentified by the memory read, such that the memory circuit at leastpartially replaces and/or substitutes the array of memory elements of atleast one of the fluidic ejection dies.
 24. The memory circuit of claim1, wherein the memory circuit at least partially replaces or substitutesa memory of the fluid ejection die of the print component.